From: Michael Zuo (mzuo@ixiacom.com)
Date: Sat Jan 27 2007 - 22:37:31 ART
I have narrowed problem down to two adjacent switches can not ping each
other over the trunk link and collected debug info as follows (note that
the ARP debug shows that CAT2 responded to ARP but CAT1 never received
the response. Also the trunk link between the two is f0/14 on both
sides, I verified the physical connection by shut/no shut on the
interface and watch the same interface go up and down on the other
switch):
CAT1(config-if)#do sh vlan
VLAN Name Status Ports
---- -------------------------------- ---------
-------------------------------
1 default active Fa0/1, Fa0/3, Fa0/5,
Fa0/7
Fa0/9, Fa0/10, Fa0/11,
Fa0/12
Fa0/15, Fa0/16, Fa0/17,
Fa0/18
Fa0/19, Fa0/20, Fa0/21,
Fa0/24
Gi0/1, Gi0/2
10 NET-10 active Fa0/2
20 NET-20 active Fa0/6
30 NET-30 active Fa0/4
40 NET-40 active
101 VLAN0101 active
102 VLAN0102 active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
3000 VLAN3000 active
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1
Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------
------
1 enet 100001 1500 - - - - - 0
0
CAT1(config-if)#do sh run int vlan 30
Building configuration...
Current configuration : 63 bytes
!
interface Vlan30
ip address 172.16.34.10 255.255.255.0
end
CAT1(config-if)#
CAT1(config-if)#
CAT1(config-if)#
CAT1(config-if)#do sh int trun
Port Mode Encapsulation Status Native vlan
Fa0/8 on 802.1q trunking 1
Fa0/13 on isl trunking 1
Fa0/14 on 802.1q trunking 1
Fa0/22 desirable 802.1q trunking 1
Fa0/23 desirable 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/8 1-4094
Fa0/13 10
Fa0/14 1,20,30,40
Fa0/22 1-4094
Fa0/23 1-4094
Port Vlans allowed and active in management domain
Fa0/8 1,10,20,30,40,101-102,3000
Fa0/13 10
Fa0/14 1,20,30,40
Fa0/22 1,10,20,30,40,101-102,3000
Fa0/23 1,10,20,30,40,101-102,3000
Port Vlans in spanning tree forwarding state and not pruned
Port Vlans in spanning tree forwarding state and not pruned
Fa0/8 1,10,20,30,40,101-102,3000
Fa0/13 10
Fa0/14 1,20,30,40
Fa0/22 1,10,20,30,40,101-102,3000
Fa0/23 1,10,20,30,40,101-102,3000
CAT1(config-if)#do sh span vlan 30
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32798
Address 0011.20a9.9280
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0011.20a9.9280
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
Fa0/4 Desg FWD 19 128.4 P2p
Fa0/8 Desg FWD 19 128.8 P2p
Fa0/14 Desg FWD 19 128.14 P2p
Fa0/22 Desg FWD 19 128.22 P2p
Fa0/23 Desg FWD 19 128.23 P2p
CAT1(config-if)#do deb arp
ARP packet debugging is on
CAT1(config-if)#do ping 172.16.34.11
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.34.11, timeout is 2 seconds:
00:28:03: IP ARP: creating incomplete entry for IP address: 172.16.34.11
interfa
ce Vlan30
00:28:03: IP ARP: sent req src 172.16.34.10 0011.20a9.9280,
dst 172.16.34.11 0000.0000.0000 Vlan30.
00:28:05: IP ARP: sent req src 172.16.34.10 0011.20a9.9280,
dst 172.16.34.11 0000.0000.0000 Vlan30.
00:28:07: IP ARP: sent req src 172.16.34.10 0011.20a9.9280,
dst 172.16.34.11 0000.0000.0000 Vlan30.
00:28:09: IP ARP: sent req src 172.16.34.10 0011.20a9.9280,
dst 172.16.34.11 0000.0000.0000 Vlan30.
00:28:11: IP ARP: sent req src 172.16.34.10 0011.20a9.9280,
dst 172.16.34.11 0000.0000.0000 Vlan30.
Success rate is 0 percent (0/5)
CAT1(config-if)#
CAT2(config-if)#do sh vlan
VLAN Name Status Ports
---- -------------------------------- ---------
-------------------------------
1 default active Fa0/2, Fa0/4, Fa0/6,
Fa0/7
Fa0/8, Fa0/9, Fa0/10,
Fa0/11
Fa0/12, Fa0/15, Fa0/16,
Fa0/17
Fa0/18, Fa0/19, Fa0/20,
Fa0/21
Fa0/24, Gi0/1, Gi0/2
10 NET-10 active
20 NET-20 active Fa0/3
30 NET-30 active Fa0/5
40 NET-40 active Fa0/1
101 VLAN0101 active
102 VLAN0102 active
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1
Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------
------
1 enet 100001 1500 - - - - - 0
0
10 enet 100010 1500 - - - - - 0
0
CAT2(config-if)#do sh run int vlan 30
Building configuration...
Current configuration : 63 bytes
!
interface Vlan30
ip address 172.16.34.11 255.255.255.0
end
CAT2(config-if)#do sh int trun
Port Mode Encapsulation Status Native vlan
Fa0/13 on isl trunking 1
Fa0/14 on 802.1q trunking 1
Fa0/22 desirable 802.1q trunking 1
Fa0/23 desirable 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/13 10
Fa0/14 1,20,30,40
Fa0/22 1-4094
Fa0/23 1-4094
Port Vlans allowed and active in management domain
Fa0/13 10
Fa0/14 1,20,30,40
Fa0/22 1,10,20,30,40,101-102
Fa0/23 1,10,20,30,40,101-102
Port Vlans in spanning tree forwarding state and not pruned
Fa0/13 10
Fa0/14 1
Fa0/22 1
Port Vlans in spanning tree forwarding state and not pruned
Fa0/23 1
CAT2(config-if)#do sh span vlan 30
VLAN0030
Spanning tree enabled protocol ieee
Root ID Priority 32798
Address 0011.20a9.9280
Cost 19
Port 14 (FastEthernet0/14)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0011.5c63.0e00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
Fa0/5 Desg FWD 19 128.5 P2p
Fa0/14 Root FWD 19 128.14 P2p
Fa0/22 Desg FWD 19 128.22 P2p
Fa0/23 Desg FWD 19 128.23 P2p
CAT2(config-if)#do deb arp
ARP packet debugging is on
CAT2(config-if)#
00:28:09: IP ARP: rcvd req src 172.16.34.10 0011.20a9.9280, dst
172.16.34.11 Vla
n30
00:28:09: IP ARP: sent rep src 172.16.34.11 0011.5c63.0e00,
dst 172.16.34.10 0011.20a9.9280 Vlan30
CAT2(config-if)#
00:28:11: IP ARP: rcvd req src 172.16.34.10 0011.20a9.9280, dst
172.16.34.11 Vla
n30
00:28:11: IP ARP: sent rep src 172.16.34.11 0011.5c63.0e00,
dst 172.16.34.10 0011.20a9.9280 Vlan30
CAT2(config-if)#
00:28:13: IP ARP: rcvd req src 172.16.34.10 0011.20a9.9280, dst
172.16.34.11 Vla
n30
00:28:13: IP ARP: sent rep src 172.16.34.11 0011.5c63.0e00,
dst 172.16.34.10 0011.20a9.9280 Vlan30
CAT2(config-if)#
00:28:15: IP ARP: rcvd req src 172.16.34.10 0011.20a9.9280, dst
172.16.34.11 Vla
n30
00:28:15: IP ARP: sent rep src 172.16.34.11 0011.5c63.0e00,
dst 172.16.34.10 0011.20a9.9280 Vlan30
CAT2(config-if)#
00:28:17: IP ARP: rcvd req src 172.16.34.10 0011.20a9.9280, dst
172.16.34.11 Vla
n30
00:28:17: IP ARP: sent rep src 172.16.34.11 0011.5c63.0e00,
dst 172.16.34.10 0011.20a9.9280 Vlan30
CAT2(config-if)#
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Michael Zuo
Sent: Saturday, January 27, 2007 5:12 PM
To: Muizebelt Danny; ccielab groupstudy; Sergey Golovanov
Subject: RE: ICMP showing encapsulation failed
I checked the following items and they all seemed OK:
1. all trunk interfaces are "trunking" under "show int trun"
2. vlan 30 is configured on both CAT1 and CAT2
3. all used interfaces are "FWD" under "show span vlan 30"
4. all interfaces are full duplex and 100 mbps under "show interface"
I turned on "deb arp" on devices and noticed that:
1. when R4 is pinging CAT1, CAT1 does not see any ARP request
2. when CAT1 is pinging R4, R4 sees the ARP requests and responds, but
CAT1 does not see the response comes back
This seems that communication from R4 to CAT1 is blocked somehow. Any
suggestions?
I also put in a temporary vlan 30 interface on CAT2, R4 can ping CAT2,
R3 can be ping CAT1, but just not across the trunk link which seems to
be cause. But I don't know why this is happening...
Thanks in advance ....
-----Original Message-----
From: Muizebelt Danny [mailto:Danny.Muizebelt@osiatis.at]
Sent: Thursday, January 25, 2007 1:12 AM
To: Michael Zuo; ccielab groupstudy
Subject: RE: ICMP showing encapsulation failed
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256
I think you didn't get an arp resolution for the 172.16.34.4 address,
that's why the encapsulation failed because there is no L3 to L2
mapping.
The reason why there is no arp resolution could be a problem with your
trunk, is it up? Is vlan 30 defined on both switches? Is the spanning
tree working properly?
Another thing I wanted to point out, if you statically configure duplex
settings on one side and leave the other side on auto then the auto side
will fall back to default half-duplex. Statically configuring duplex
settings switches off the auto negotiation. So either both sides on auto
or both statically configured.
Danny Muizebelt
CCIE #17353
- -----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Michael Zuo
Sent: Donnerstag, 25. Jdnner 2007 08:22
To: ccielab groupstudy
Subject: ICMP showing encapsulation failed
Hi group,
I am scratching my head on this one (probably something basic), please
help! And thanks in advance....
R3(f0/1)---------(f0/4)CAT1(f0/14)-----------(f0/14)CAT2(f0/5)----------
- -----R4(f0/0)
When I ping from R3 to R4, I get encapsulation failed message on R3:
R3(config-if)#do ping 172.16.34.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.34.4, timeout is 2 seconds:
2d07h: IP: tableid=0, s=172.16.34.3 (local), d=172.16.34.4
(FastEthernet0/1), ro
uted via RIB
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, send
ing
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, enca
psulation failed.
2d07h: IP: tableid=0, s=172.16.34.3 (local), d=172.16.34.4
(FastEthernet0/1), ro
uted via RIB
2d07h: IP: s=172.16.34.3 (local), d=172.16.34.4 (FastEthernet0/1), len
100, send
Ing
Configuration:
R3:
=======
R3(config-router)#do sh run int f0/1
Building configuration...
Current configuration : 96 bytes
!
interface FastEthernet0/1
ip address 172.16.34.3 255.255.255.0
duplex auto
speed auto
end
R3(config-router)#
CAT1:
========
CAT1(config)#do sh run int f0/4
Building configuration...
Current configuration : 97 bytes
!
interface FastEthernet0/4
switchport access vlan 30
switchport mode access
duplex full
end
CAT1(config)#do sh run int f0/14
Building configuration...
Current configuration : 137 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,20,30,40
switchport mode trunk
CAT1(config-if)#do sh run int vlan 30
Building configuration...
Current configuration : 63 bytes
!
interface Vlan30
ip address 172.16.34.10 255.255.255.0
end
CAT2:
CAT2(config-if)#do sh run int f0/5
Building configuration...
Current configuration : 97 bytes
!
interface FastEthernet0/5
switchport access vlan 30
switchport mode access
duplex full
end
CAT2(config-if)#do sh run int f0/14
Building configuration...
Current configuration : 137 bytes
!
interface FastEthernet0/14
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,20,30,40
switchport mode trunk
end
CAT2(config-if)#
R4
=======
R4(config-router)#do sh run int f0/0
Building configuration...
Current configuration : 96 bytes
!
interface FastEthernet0/0
ip address 172.16.34.4 255.255.255.0
duplex auto
speed auto
end
R4(config-router)#
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